/*
 * (c) Copyright 2007, 2008 Hewlett-Packard Development Company, LP
 * All rights reserved.
 * [See end of file]
 */

package arq.examples.bgpmatching;

import com.hp.hpl.jena.query.ARQ;
import com.hp.hpl.jena.query.Query;
import com.hp.hpl.jena.query.QueryExecution;
import com.hp.hpl.jena.query.QueryExecutionFactory;
import com.hp.hpl.jena.query.QueryFactory;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.ModelFactory;
import com.hp.hpl.jena.rdf.model.Property;
import com.hp.hpl.jena.rdf.model.Resource;
import com.hp.hpl.jena.sparql.engine.main.StageGenerator;
import com.hp.hpl.jena.sparql.util.QueryExecUtils;
import com.hp.hpl.jena.sparql.util.StringUtils;

/**
 * Example to execute a query but handle the basic graph patterns in the query
 * in some special way. Stages are one step in executing a basic graph pattern
 * (BGP). A StageGenerator builds a StageList and the stage list is executes
 * with the output (a QueryIterator) of the previous stage fed int the current
 * stage.
 */

public class StageAltMain {
	static String NS = "http://example/";

	public static void main(String[] argv) {
		String[] queryString = { "PREFIX ns: <" + NS + ">", "SELECT ?v ",
				"{ ?s ns:p1 'xyz' ;", "     ns:p2 ?v }" };

		// The stage generator to be used for a query execution
		// is read from the context. There is a global context, which
		// is cloned when a query execution object (query engine) is
		// created.

		StageGenerator stageGenAlt = new StageGeneratorAlt();

		// The normal stage generator is registerd in the global context.
		// This can be replaced, so that every query execution uses the
		// alternative stage generator, or the cloned context can be
		// alter so that just one query execution is affected.

		// Change the stage generator for all queries ...
		if (false)
			ARQ.getContext().set(ARQ.stageGenerator, stageGenAlt);

		Query query = QueryFactory.create(StringUtils.join("\n", queryString));
		QueryExecution engine = QueryExecutionFactory.create(query, makeData());

		// ... or set on a per-execution basis.
		if (true)
			engine.getContext().set(ARQ.stageGenerator, stageGenAlt);

		QueryExecUtils.executeQuery(query, engine);
	}

	private static Model makeData() {
		Model model = ModelFactory.createDefaultModel();
		Resource r = model.createResource(NS + "r");
		Property p1 = model.createProperty(NS + "p1");
		Property p2 = model.createProperty(NS + "p2");
		model.add(r, p1, "xyz");
		model.add(r, p2, "abc");
		return model;
	}
}

/*
 * (c) Copyright 2007, 2008 Hewlett-Packard Development Company, LP All rights
 * reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer. 2. Redistributions in
 * binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other
 * materials provided with the distribution. 3. The name of the author may not
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */